let person = {
    age: 25,
    name: 'Justin'
}
const byRef = (myObj) => {
    myObj.age = 30
}
const byRef2=(obj)=>{
    obj.age=30;
    // 重新赋值，赋值以后和原来的对象不再指向同一地址
    obj={age:50}
    obj.age=60
}
byRef2(person);
console.log(person.age);